In certain types of medical emergencies, Cardiopulmonary Resuscitation (CPR) needs to be delivered to a patient. CPR includes repeatedly compressing the chest of the patient, to cause their blood to circulate some. CPR also includes delivering rescue breaths to the patient. A number of people are trained in CPR, just in case, even though they are not trained in the medical professions.
The chest compressions are intended to cause the blood to continue circulating, so as to prevent damage to organs like the brain. In some instances, the chest compressions merely maintain the patient, until a more definite therapy is made available, such as defibrillation. Defibrillation is an electrical shock deliberately delivered to a person, in the hope of correcting their heart rhythm.
A problem is that CPR is sometimes ineffective at providing blood circulation to the patient. That can happen whether or not the rescuer who performs the CPR is part of the medical profession. The most frequent example of such ineffectiveness is compressions that are not deep enough, or not frequent enough, or do not last long enough. Even the best trained rescuers can become fatigued after delivering CPR, with the compressions deteriorating in quality. And that is without even accounting for the emotions of the moment, which might impact a lay rescuer.
The risk of ineffective chest compressions has been addressed with CPR feedback devices, some of which are standalone, while others are integrated or cooperate with defibrillators. These devices actually detect the depth and frequency of compressions that the rescuer is performing, and give feedback to the rescuer that is specifically attuned to what the rescuer is doing. This feedback is in accordance with how well the rescuer is meeting guidelines, such as those of the American Heart Association. These prompts and other instructions and can help the rescuer focus, even if the latter cannot remember their training.
Reaching the appropriate depth is difficult. The recommended depth is a range. If the actual depth is less than the range, not enough blood is moved within the patient. If the depth exceeds the range, the patient's ribs may break. And, even for experienced rescuers, it is sometimes hard to discern the appropriate depth. Reaching the appropriate depth is even more difficult if the patient is on a flexible mattress that partly recedes, as the rescuer is pushing from the top. And CPR compressions can be even more challenging if the rescuer has to deliver them in a moving ambulance.
An alternative to manual CPR are CPR chest compression machines. Such machines have been known by a number of names, such as mechanical CPR devices, cardiac compressors, external chest compression machines, and so on. One such machine is the LUCAS® available from Physio-Control, Inc., Redmond, Wash.
CPR chest compression machines repeatedly compress and release the chest of the patient. Such machines can be programmed so that they will compress and release at the recommended rate, and to a specific depth within the recommended range. Some CPR chest compression machines have a rigid back plane upon which the patient is placed in a supine position.